This invention relates in general to fluid dispensing apparatus, and more particularly to lubricant dispensing apparatus for delivering a charge of lubricant to a point of lubrication, e.g. by spraying the lubricant on an item to be lubricated.
The invention has been developed primarily though not exclusively as a means for efficiently and reliably carrying out in the field the lubrication of threaded connections of drill tubes used in drilling long blast holes in oil and gas exploration operations, lubrication of the connections facilitating the end-to-end assembly of the drill tubes. Heretofore, lubrication of such connections has generally been carried out either manually or (frequently inadequately) with air-operated pumps. Manual lubrication requires the drilling operator to lose productive time by having to get out of his cab to apply the lubricant to the threaded connection by hand. Application by use of air-operated pumps to spray the lubricant on the threaded connections is generally ineffective to provide a good quality spray at temperatures ranging from +160.degree. F. (+71.degree. C. ) to -20.degree. F. (-29.degree. C. ); at low temperatures air-operated pumps may even become inoperable. The invention has also taken into account the problem that certain zinc or copper-based greases specially formulated for lubricating drill tube connections are very difficult to pump and spray.